A local Kurdish official said today that Iranian authorities turned back wounded Islamic militants seeking medical care after a U.S. attack against their enclave in northern Iraq.

The decision to send back the injured Ansar al-Islam militants marked a reversal of Iranian policy, which had been to facilitate the shipment of military supplies to the extremist Kurdish organization. The shift coincided with the arrival of U.S. Special Operations forces in northern Iraq to engage the Ansar fighters and eliminate the group, which Washington portrays as allied with the al Qaeda network of Osama bin Laden.

The U.S. offensive here began Saturday, when about 50 Tomahawk cruise missiles from U.S. warships in the Red Sea slammed into Ansar positions, and it has continued with several subsequent missile attacks. After the first volley, the Ansar militants gathered their wounded and limped across the border into Iran, seeking medical attention, according to Kurdish officials here.

"They went inside one kilometer, but then Iranians made them go back," said Muhammad Haji Mahmud, leader of the Kurdistan Socialist Democratic Party, which controls territory just north of the area.

The turnabout impressed Kurdish officials, who have publicly complained of Iran's evident support for Ansar. They said the sudden shift in sympathy reflects Iranian anxiety about the possibility of becoming a U.S. target. President Bush has said Iran is part of an "axis of evil," along with North Korea and Iraq.

"They're scared," a Kurdish official said of the Iranians. "They did not believe it until the cruise missiles arrived."

Kurdish officials said a combined U.S. and Kurdish ground force plans to attack the Ansar enclave soon. That assault, they said, will be supported from the air by helicopter gunships that began arriving early Sunday at a closely guarded airstrip at Bakrajo, just outside Sulaymaniyah, a regional capital in the northeastern part of the country, near the Iranian border.

Witnesses said the helicopters arrived on military cargo flights that also ferried in at least 200 U.S. soldiers, and logistics and targeting specialists. Scores of the U.S. forces were sighted in a convoy headed toward the Kurds' staging area later on Sunday.

Area residents said the helicopters, after being lifted off the cargo planes and quickly re-assembled on the reconditioned airstrip, were flown to a closely guarded compound of the Patriotic Union of Kurdistan (PUK), the party that controls this section of northern Iraq, where Kurds have enjoyed freedom from the Baghdad government since 1991 under the protection of U.S. and British fighter patrols.

Some 8,000 PUK fighters gathered in the Halabja Valley, about 35 miles south of here, are expected to participate in the assault on Ansar, whose enclave lies in the valley along the Iranian border. But attack helicopters could more easily reach the caves in which the extremists have taken refuge since the airstrikes began.

Civilians flee the northeastern Iraqi town of Khurmal, less than 10 miles from the Iranian border. U.S. forces fired Tomahawk cruise missiles at a suspected Ansar al-Islam enclave Saturday in the nearby Halabja Valley. Khurmal residents leave their homes before an expected ground assault by U.S. forces. Injured Ansar militants were recently turned away at the Iranian border.